IN-FURROW TERBUFOS REDUCES FIELD AND SWEET CORN (ZEA-MAYS) TOLERANCE TO NICOSULFURON

Field experiments were conducted in Michigan, Minnesota, and Wisconsin in 1990 to explore interactions between nicosulfuron applied POST and terbufos insecticide at 0.06 or 0.11 g ai/m of row applied in-furrow on 'Pioneer 3751' field corn and 'Jubilee' sweet corn. Nicosulfuron at 0, 70, and 140 g ai/ha plus nonionic surfactant and 28% nitrogen fert ilizer was applied to both corn types. Field corn response to nicosulf uron and terbufos was similar at all locations, whereas sweet corn inj ury varied with location, Nicosulfuron injured field corn more when ap plied at the four-leaf than the three-leaf stage. Injury to both corn types increased as nicosulfuron rate increased or when applied followi ng terbufos. Nicosulfuron at 140 g/ha without terbufos did not reduce yield of either corn type; however, corn previously treated in-furrow with terbufos reduced yield.